Arbuscular mycorrhizal fungi reduce soil N2O emissions by altering root traits and soil denitrifier community composition

• Published in: The Science of the total environment 2024-07, Vol.933, p.173065-173065, Article 173065
• Main Authors: He, Tangqing, Lin, Wei, Yang, Shuo, Du, Jiaqi, Giri, Bhoopander, Feng, Cheng, Gilliam, Frank S., Zhang, Fuliang, Zhang, Xiaoquan, Zhang, Xuelin
• Format: Article
• Language: English
• Subjects: Agro-ecosystem; Denitrifier microbes; Mycorrhizal symbiosis; Nitrous oxide; Nutrient uptake; Plant root traits
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2024.173065

Arbuscular mycorrhizal fungi (AMF) increase the ability of plants to obtain nitrogen (N) from the soil, and thus can affect emissions of nitrous oxide (N2O), a long-lived potent greenhouse gas. However, the mechanisms underlying the effects of AMF on N2O emissions are still poorly understood, particularly in agroecosystems with different forms of N fertilizer inputs. Utilizing a mesocosm experiment in field, we examined the effects of AMF on N2O emissions via their influence on maize root traits and denitrifying microorganisms under ammonia and nitrate fertilizer input using 15N isotope tracer. Here we show that the presence of AMF alone or both maize roots and AMF increased maize biomass and their 15N uptake, root length, root surface area, and root volume, but led to a reduction in N2O emissions under both N input forms. Random forest model showed that root length and surface area were the most important predictors of N2O emissions. Additionally, the presence of AMF reduced the (nirK + nirS)/nosZ ratio by increasing the relative abundance of nirS-Bradyrhizobium and Rubrivivax with ammonia input, but reducing nosZ-Azospirillum, Cupriavidus and Rhodopseudomonas under both fertilizer input. Further, N2O emissions were significantly and positively correlated with the nosZ-type Azospirillum, Cupriavidus and Rhodopseudomonas, but negatively correlated with the nirS-type Bradyrhizobium and Rubrivivax. These results indicate that AMF reduce N2O emissions by increasing root length to explore N nutrients and altering the community composition of denitrifiers, suggesting that effective management of N fertilizer forms interacting with the rhizosphere microbiome may help mitigate N2O emissions under future N input scenarios. [Display omitted] •The effects of AMF and roots on N2O emissions were studied with 15N isotope tracer.•AMF altered maize root traits, leading to a decrease in soil N2O emissions.•AMF reduced (nirK + nirS)/nosZ ratio and altered denitrifier community composition.•N fertilizer management interacting with the microbiome may reduce N2O emissions.